From patchwork Tue Apr 12 06:28:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 560639 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C39E5C4332F for ; Tue, 12 Apr 2022 07:07:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344814AbiDLHJ3 (ORCPT ); Tue, 12 Apr 2022 03:09:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58622 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349202AbiDLHBo (ORCPT ); Tue, 12 Apr 2022 03:01:44 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E29943AC8; Mon, 11 Apr 2022 23:46:51 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id AA6B5CE1ACD; Tue, 12 Apr 2022 06:46:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFA6FC385A1; Tue, 12 Apr 2022 06:46:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649746008; bh=7IHmMLqdZHm/f+ayP8iTbx5IYzCMNs867hz03mwV7B8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vNePWhKeAtn/AQO5rKAM7Q+xfcYiHiEm7Wbtd02CIEr2DmoYV4NIyaxfVJ/FGJ94w 1d4zUNIB802r8pDfoSdwDoUCF/cHvBXRxHx8EIF0mQkNziu5bS5Rx05qUWaa21D0QI 0YCCpyppn/I2hqIzGwwc5Wmys+zfcaOdqiQdHNiY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maxime Ripard , Stephen Boyd , Sasha Levin Subject: [PATCH 5.15 126/277] clk: Enforce that disjoints limits are invalid Date: Tue, 12 Apr 2022 08:28:49 +0200 Message-Id: <20220412062945.686746968@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220412062942.022903016@linuxfoundation.org> References: <20220412062942.022903016@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Maxime Ripard [ Upstream commit 10c46f2ea914202482d19cf80dcc9c321c9ff59b ] If we were to have two users of the same clock, doing something like: clk_set_rate_range(user1, 1000, 2000); clk_set_rate_range(user2, 3000, 4000); The second call would fail with -EINVAL, preventing from getting in a situation where we end up with impossible limits. However, this is never explicitly checked against and enforced, and works by relying on an undocumented behaviour of clk_set_rate(). Indeed, on the first clk_set_rate_range will make sure the current clock rate is within the new range, so it will be between 1000 and 2000Hz. On the second clk_set_rate_range(), it will consider (rightfully), that our current clock is outside of the 3000-4000Hz range, and will call clk_core_set_rate_nolock() to set it to 3000Hz. clk_core_set_rate_nolock() will then call clk_calc_new_rates() that will eventually check that our rate 3000Hz rate is outside the min 3000Hz max 2000Hz range, will bail out, the error will propagate and we'll eventually return -EINVAL. This solely relies on the fact that clk_calc_new_rates(), and in particular clk_core_determine_round_nolock(), won't modify the new rate allowing the error to be reported. That assumption won't be true for all drivers, and most importantly we'll break that assumption in a later patch. It can also be argued that we shouldn't even reach the point where we're calling clk_core_set_rate_nolock(). Let's make an explicit check for disjoints range before we're doing anything. Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20220225143534.405820-4-maxime@cerno.tech Signed-off-by: Stephen Boyd Signed-off-by: Sasha Levin --- drivers/clk/clk.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 5cef73a85901..d6dc58bd07b3 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -631,6 +631,24 @@ static void clk_core_get_boundaries(struct clk_core *core, *max_rate = min(*max_rate, clk_user->max_rate); } +static bool clk_core_check_boundaries(struct clk_core *core, + unsigned long min_rate, + unsigned long max_rate) +{ + struct clk *user; + + lockdep_assert_held(&prepare_lock); + + if (min_rate > core->max_rate || max_rate < core->min_rate) + return false; + + hlist_for_each_entry(user, &core->clks, clks_node) + if (min_rate > user->max_rate || max_rate < user->min_rate) + return false; + + return true; +} + void clk_hw_set_rate_range(struct clk_hw *hw, unsigned long min_rate, unsigned long max_rate) { @@ -2347,6 +2365,11 @@ int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max) clk->min_rate = min; clk->max_rate = max; + if (!clk_core_check_boundaries(clk->core, min, max)) { + ret = -EINVAL; + goto out; + } + rate = clk_core_get_rate_nolock(clk->core); if (rate < min || rate > max) { /* @@ -2375,6 +2398,7 @@ int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max) } } +out: if (clk->exclusive_count) clk_core_rate_protect(clk->core);